Fractional catalytic pyrolysis of biomass

ABSTRACT

Methods for fractional catalytic pyrolysis which allow for conversion of biomass into a slate of desired products without the need for post-pyrolysis separation are described. The methods involve use of a fluid catalytic bed which is maintained at a suitable pyrolysis temperature. Biomass is added to the catalytic bed, preferably while entrained in a non-reactive gas such as nitrogen, causing the biomass to become pyrolyzed and forming the desired products in vapor and gas forms, allowing the desired products to be easily separated.

CLAIM OF PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/953,266, filed Aug. 1, 2007, the disclosure of which is herebyincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to processes for pyrolytic conversion ofbiomass materials into fuels and other usable products. The presentinvention describes a pyrolytic process wherein the biomass materialsare selectively converted into desired products eliminating potentialsecondary, post-pyrolysis, processing steps.

BACKGROUND OF THE INVENTION

Conventional rapid pyrolysis (RP) of biomass is a thermal treatmentprocess in the absence of air, which produces char, liquid, and gaseousproducts [1-14]. In these processes, the pyrolysis temperatures rangefrom 450° C.-600° C. and vapor residence times are less than one secondto five seconds. In the RP process, liquid production is maximized atthe expense of gaseous and solid products. The liquid product (bio-oilor biocrude) is generally unstable, acidic, corrosive, viscous, and hashigh moisture content [15-18]. The poor stability of biocrude oils isattributed to the char and alkali metals in the oil, which catalyzesecondary reactions during storage [17]. However, if the hot pyrolysisvapors are filtered to reduce the char content before condensation, thestability of the oil is improved considerably [18].

Biocrude oils are complex mixtures of carbohydrate and lignin thermaldecomposition products, which cannot be used for most biobased productsand fuel applications except after considerable secondary processing.Secondary processing such as catalytic upgrading [19-26], liquid-liquidextraction [27-29], or gasification [30-35] increase the cost of thefinal product and make it less economically competitive relative tofossil derived products.

Catalytic studies of biomass pyrolysis products have focused onupgrading of pyrolysis oils (post pyrolysis catalysis) to higher valueproducts [19-26], but most of these studies reported low yields ofhydrocarbons, high coke/char yields, and rapid deactivation of thecatalysts. Other catalytic studies of whole biomass feedstocks focusedon gasification to synthesis gas [30-35], but fractional pyrolysis havenot been reported in published literature.

Biomass feedstocks are composed of structural (lignin, cellulose, andhemicellulose) and non-structural (extractives) components, which havedistinct chemical properties. It is conceivable to selectively convertthe biomass constituents to a defined slate of chemicals and separatethese products in situ (fractional pyrolysis) without necessarily goingthrough secondary extraction and upgrading processes. Fractionalpyrolysis is defined as a selective in situ conversion of biopolymers todesired products. This approach is aided by catalysts and can produce anarrow slate of pyrolysis products, which can be tailored to specificapplications. This approach has potential application for convertingwhole biomass feedstocks, biomass-to-ethanol residues, and organosolvlignins (pulping residues) into high-value products. Potential productsinclude synthesis gas, phenol formaldehyde resins, phosphate esters,magnetic wire, cleaning and disinfectant compounds, ore floatation, andmiscellaneous applications.

As such, there remains a need in the art for processes to selectivelyconvert biomass components in situ into suitable products using suitablecatalysts and thus eliminating potential secondary processing steps.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide processes for thefractional catalytic pyrolysis of biomass feedstocks. The processes ofthe present invention both catalyze the pyrolysis of biomass feedstocksand isolate useful pyrolysis products, eliminating the need for furtherprocessing steps.

The processes of the present invention involve use of a fluidizedcatalyst bed maintained at a temperature suitable for pyrolysis ofbiomass. The biomass is entrained in the fluid used to fluidize thecatalyst bed, causing the biomass to be delivered to the catalyst bedand be pyrolyzed. The vapors and gases released during pyrolysis arecarried from the fluidized catalyst bed by the fluid, where they arethen collected in various fractions. As the pyrolysis products arecollected in fractions, they are sufficiently isolated to be suitablefor downstream uses, and no further processing steps are needed. Theprocesses of the present invention can provide many useful pyrolysisproducts from a wide variety of biomass feedstocks without the need forfurther processing of these products.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1. ¹³C-NMR spectra of fractional catalytic pyrolysis liquid productof hybrid poplar wood collected from the electrostatic precipitator(ESP).

FIG. 2. ¹³C-NMR spectra of fractional catalytic pyrolysis liquid productof hybrid poplar wood from the chilled water (second) condenser.

FIG. 3. ¹³C-NMR spectrum of conventional rapid pyrolysis liquid productof hybrid poplar wood.

FIG. 4. A plot of the molecular weight distribution of hybrid poplarcatalytic pyrolysis oils and phenol/neutral fraction extracted fromsugar cane bagasse conventional rapid pyrolysis oils: a) bagassephenol/neutral fraction; b) hybrid poplar catalytic pyrolysis oils.

FIG. 5. A plot of the variation of carbon monoxide and carbon dioxidecontent during fractional and conventional pyrolysis of hybrid poplarwood.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides processes for fractional catalyticpyrolysis of biomass materials. The processes of the present inventionallow for the in situ conversion of biomass components into suitableproducts, eliminating the need for additional processing steps.

The processes of the present invention involve the use of a suitablecatalyst in a fluidized bed pyrolysis system. In typical embodiments ofthe present invention, the reactor used for performing the pyrolysis isa fluidized bed reactor as is well known in the art. Examples offluidized bed reactors can be found in Howard, J. R. (1989). “FluidizedBed Technology Principles and Applications.” New York, N.Y.: AdamHigler; Tavoulareas, S. (1991.) Fluidized-Bed Combustion Technology.**Annual Reviews Inc.** 16, 25-27; and Trambouze, P., & Euzen, J.(2004). “Chemical Reactors: From Design to Operation.” (R. Bonormo,Trans.). Paris: Editions Technip, which are all hereby incorporated byreference. In the system of the present invention, the fluidizing mediumis a suitable catalyst, and the bed is fluidized with a suitable fluid.

The biomass to be pyrolyzed is typically ground to a small particle sizein order to effect rapid pyrolysis. The biomass may be ground in a milluntil the desired particle size is achieved. Typically, the particlesize of the biomass to be pyrolyzed is a particle size sufficient topass through a 1-mm screen up to a particle size sufficient to passthrough a 30-mm screen.

Various type of biomass may be pyrolyzed using the processes of thepresent invention. Biomass materials including whole plant materials,biomass residues such as residues formed during ethanol production, suchas corn stover, and residues formed during distillation, such asdistiller's waste grain, switchgass, and organosolv lignins can be usedas feedstock for the processes of the present invention. In certainembodiments of the invention, wood is used as the biomass feedstock. Itis contemplated that any biomass feedstock which is suitable for use ina rapid pyrolysis system can be used with in the fractional catalyticpyrolysis processes of the present invention.

The biomass to be pyrolyzed is loaded into an entrainment compartment tobe carried into the fluidized bed by the fluid. The biomass may beloaded into a feed hopper or other device which allows for it to bedelivered to the entrainment compartment in a suitable amount. In thismanner, a constant amount of biomass is delivered into the entrainmentcompartment.

Once the biomass enters the entrainment compartment, it is carried bythe fluid to the reactor bed. In certain embodiments of the presentinvention, the fluid used is nitrogen gas. However, it is alsocontemplated that other non-oxidizing fluids could be used in theprocesses of the present invention. It is further contemplated that thepyrolysis gas produced during the processes can be recycled and used asthe entrainment fluid. In this manner, the costs of performing thepyrolysis can be greatly reduced.

The fluid carries the biomass from the entrainment compartment to thefluidized bed through a feeder tube. Typically, the feeder tube iscooled in some manner to maintain the temperature of the biomass beforeit enters the fluidized bed. The feeder tube may be cooled by jacketingthe tube, typically with an air-cooled or liquid-cooled jacket. However,it is also contemplated that the feed tube not be cooled.

The fluidized bed of the reactor comprises a catalyst suitable toproduce the desired products. In certain embodiments of the presentinvention, is the catalyst VPISU-001, which is also known as H-ZSM-5, analumnosilicate zeolite catalyst sold by Exxon Mobil of Irving, Tex. Itis also contemplated that other zeolite catalysts can be used in theprocesses of the present invention. Further, it is contemplated thatsuper acid catalysts, such as sulfated zirconium super acid catalysts,can be used for performing the processes of the present invention.

Depending on the catalyst used and the desired reaction products, thecatalyst temperature may be adjusted. In certain embodiments, thecatalyst temperature may be between about 400° C. and about 650° C.,more preferably between about 450° C. and 600° C., and most preferablyabout 500° C. The flow rate of the fluid is set so that the apparentpyrolysis vapor residence time is about 1 s, however, other longer orshorter vapor residence times, such as about 0.5 to about 5 seconds, mayalso be used with the processes of the present invention. Gas flow andother parameters, such as temperature and pressure, may be monitoredfrom a single data acquisition unit, such as an Omega data acquisitionunit from Omega Engineering, Inc. of Stamford, Conn.

The biomass feedstock may be fed into the reactor for as long as isnecessary to process the desired amount of feedstock. A pyrolysis runmay be as short as minutes and may be as long as several hours asneeded. The catalysts used in the described systems retain theircatalytic activity for extended periods of time, allowing for longreaction times. The rate at which biomass feedstock may be fed into thereactor may be varied depending, with typical feed rates of about 50 toabout 150 g/h being used and a feed rate of about 100 g/h beingpreferable.

The temperature of different parts of the reactor may be measured andregulated using temperature devices known in the art such asthermocouples. If such devices are used, they may be linked to the dataacquisition unit. Typically, measurements may be taken and thetemperature regulated in the catalyst bed, directly above the bed, andat the exit of the reactor. The catalyst bed temperature may be measuredand maintained as described above. It is desirable to have thetemperature above the bed and at the exit zone of the reactor to be setat a lower temperature than the catalysts to avoid cracking of thepyrolysis products. The temperature of the area above the bed and theexit zone may be the same or different, and may be between about 10° andabout 100° C. less than the temperature of the catalysts, with apreferred temperature difference of about 50° C.

The gases and vapors exiting the reactor may be passed through a filterto remove and solids entrained in the exiting fluid. If filters areused, it is preferred that they be hot gas filters to preventcondensation of the pyrolysis vapors. When used, the hot gas filters maybe kept at a suitable temperature to prevent condensation, for examplebetween about 3000 to about 500° C. The reactor may have pressure gaugesthat measure the pressure at various points in the fluid stream. Totalgas flow through the system may be determined by a rotameter. Feedbackfrom these instruments may also be transmitted to the data controlsystem.

After the pyrolysis vapors exit the reactor, they are passed through acondensation train to collect the desired products. Typically, thecondensation train will comprise one or more chilled water condensers,one or more electrostatic precipitator and one or more coalescencefilter, as are well known in the art, all of which will be connected inseries. While the order of the condensers can be varied, it is typicalthat the first condenser is a water cooled condenser. When used, theelectrostatic precipitator may be kept at a voltage of about 15 to about25 kV, more preferably between about 18 to about 20 kV. The voltage ofthe electrostatic precipitator may also be regulated by the dataacquisition unit. All gasses that pass through the condensation trainmay also be collected at the end of the train.

Oils and other products are recovered from the various condensers in thecondensation train to form isolated pyrolysis products. The productsisolated from at least one of the condensers will be pyrolysis productswhich are ready for use as fuels or chemical feedstocks. The isolatedpyrolysis products will have low moisture content, lower viscosity andwill be less acidic and corrosive than normal rapid pyrolysis products.Preferably, one or more of the collected fractions will containphenolics with little to no carbohydrate pyrolysis products. Productsthat may be obtained using the processes of the present inventioninclude phenols, cresols, catechols, guaiacol, methyl-substitutedphenols, indene, substituted napthalene and other aromatics. Typically,the fractions of desired phenolics will contain little to no benzene,toluene, xylenes or other undesired aromatics. Of course, the pyrolysisproducts obtained will vary depending upon the biomass feedstock andcatalysts used. Gas collected from the reactor may contain synthesis gasand other useful gases. Char and coke solids may remain in the reactor,and may be separated from the catalyst bed and collected. C₁-C₄hydrocarbons may also be produced using the processes of the presentinvention. These hydrocarbons may be steam reformed into hydrogen richgas or may be used in other applications.

As the pyrolysis products produced using the processes of the presentinvention are produced at relatively moderate temperatures, they aresuitable for more downstream processing applications than productsproduced through higher temperature processes, such as oxidativeprocesses. Further, as the pyrolysis products of the present inventionare produced at lower temperature, they are less likely to includeimpurities that are formed in processes that take place at about 900° C.and above.

Overall, potential pyrolysis products may have applications as fuels,adhesives, synthesis gas, phenol formaldehyde resins, phosphate esters,magnetic wire, cleaning and disinfectant compounds, ore floatation andother applications. Importantly, the pyrolysis products obtained will bein conditions that are suitable for use in other applications withoutthe need for extensive secondary processing steps, as are needed withrapid pyrolysis products. Further, non limiting, examples of potentialpyrolysis products are given in the examples below.

Pyrolysis products may be analyzed using techniques well known in theart, such as gas chromatography/mass spectrometry (GC/MS), gelpermeation chromatography (GPC), and nuclear magnetic resonance (NMR).Non-limiting examples of analysis of pyrolysis products are shown in theexamples below.

Non-limiting examples of fractional catalytic pyrolysis processes aregiven below. It should be apparent to one of skill in the art that thereare variations not specifically set forth herein that would fall withinthe scope and spirit of the invention as claimed below.

EXAMPLES Example 1 Preparation of Feedstocks and Catalyst

The feedstock used for this experiment was a hybrid poplar whole woodground in a Wiley mill (model 4) to pass a 1-mm screen. The moisturecontent of the feed was 5%. A proprietary catalyst (VPISU-001-H-ZMS-5zeolite from Exxon Mobil of Irving, Tex.) was used for the runs. Twohundred gram batches of this catalyst were used for the fluidized bedpyrolysis experiments.

Example 2 Fluidized Bed Pyrolysis

The reactor consisted of a 50 mm (2-in) schedule 40 stainless steelpipe, 500 mm (20 in.) high (including a 140-mm (5.5 in.) preheater zonebelow the gas distribution plate) and equipped with a 100-μm porousmetal gas distributor. The fluidizing medium was the above proprietarycatalyst, and the bed was fluidized with nitrogen. The reactor wasexternally heated with a three zone electric furnace. The reactor tubecontained a bubbling fluid bed with back mixing of the feed andcatalyst.

The biomass was loaded into a feed hopper (batch-wise) and conveyed by atwin-screw feeder into an entrainment compartment where high-velocitynitrogen gas entrained the feed and carried it through a jacketedair-cooled feeder tube into the fluidized bed. The pyrolysis temperaturewas maintained at 500° C. and the apparent pyrolysis vapor residencetime was about 1 s. The apparent residence time of gases and vapors isdefined as the free reactor volume (the empty reactor volume minus thevolume of hot catalyst) divided by the entering gas flow rate expressedat reactor conditions. A typical run lasted for 2-3 h, and the feed ratewas 100 g/h. The feed rate, gas flow rate, and reactor temperature werekept constant during each run.

The catalyst and reactor temperatures were measured and controlled bythree K-thermocouples inserted into a thermal well dipping into thecatalyst bed. One thermocouple spanned the full length of the thermalwell and this was used to measure and control the catalyst bedtemperature. The next thermocouple was maintained above the bed heightand the third thermocouple measured the exit temperature of thepyrolysis vapors and gases. The catalyst bed temperature was maintainedat 500° C., but the area above the bed and the exit zone were nominallyset at 450° C. to avoid any possible cracking of the pyrolysis productsin these zones.

Pyrolysis gases and vapors exiting the reactor passed through a heatedhot gas filter unit to separate char/ash and any entrained catalyst. Thehot-gas filter temperature was maintained at 400° C. to avoidcondensation of the pyrolysis vapors. The pyrolysis gases and vaporswere then passed through a condensation train consisting of a chilledwater condenser, an electrostatic precipitator, and a coalescence filter(all connected in series). The electrostatic precipitator was maintainedat 18-20 kV throughout the run. The temperatures, gas flow rates,pressure drop across the reactor, and electrostatic precipitator voltagewere controlled and/or monitored by an Omega data acquisition unit soldby Omega Engineering, Inc. of Stamford, Conn. Pressure drop across thehot gas filter was monitored by a pressure gage.

The gas samples were collected in syringes and analyzed after each run.Total gas flow was measured by a rotameter. To ensure good mass closure,the entire setup (excluding the rotameter) was weighed before and afterthe run. The pyrolysis oils collected from each condenser receiver werekept separate and analyzed by GC/MS, GPC, and ¹³C-NMR. The residualpyrolysis oils on the walls of the condensers were recovered (afterweighing the pyrolysis unit) by rinsing the condensers with acetone. Theacetone was evaporated under vacuum (40° C. and 61.3 kPa), and the oilsrecovered. None of the oils recovered from the acetone wash was used foranalysis, because there is always some residual acetone associated withthis fraction and the potential of losing some volatile componentsduring the operation precludes it from being a true representative ofthe pyrolysis oils.

The char/coke content was determined by weighing the reactor/catalystand hot gas filter before and after each run, the difference in weightwas recorded as char/coke. No attempt was made to differentiate betweenthe char and coke and no further analysis was done.

Example 3 Gas Analysis

The pyrolysis gases were sampled and analyzed on a Shimadzu GC14A soldby Shimadzu Corp. of Kyoto, Japan. Three packed columns (Porapak N,molecular sieve 5A, and Hysep Q, sold by Agilent Technologies of SantaClara, Calif.) connected in series were used to analyze the gases. Theoven was temperature programmed and a thermal conductivity detector wasused. The chromatogram conditions are shown below:

-   -   Columns: 3.2 mm×2 m Porapak N 80/100 mesh; and 3.2 mm×2 m        Molecular sieve 5A 60/80 mesh, and 3.2×2 m Hysep Q 100/180 mesh.    -   Detector: Thermal conductivity (TCD) at 200° C.    -   Injection temperature: 150° C.    -   Carrier gas: helium at 30 mL/min.    -   Oven temperature programming:    -   Initial temperature: 30° C. for 3.00 min.    -   Level 1: Heating rate 20° C./min; final temperature 60° C. for 4        min.    -   Level 2: Heating rate 25° C./min; final temperature 200° C. for        9 min.

Method of separation: Column 1 (Porapak N) separated the sample into twofractions: N₂, O₂, CH₄ and CO which eluted quickly as one peak and weredirected to column 2 (molecular sieve 5A) which separated these gases.The other fraction of the sample, which was composed of CO₂, C₂-C₄ gasesmoved very slowly and were directed to column 3 (Hysep Q) whichseparated them into various components. The column switching wasaccomplished by automatic valve switching using Shimadzu CLASSVPprogram. The gas chromatogram was processed using the Shimadzu CLASSVPprogram.

Example 4 Pyrolysis Products

During first half hour of pyrolysis, there was very little condensationof pyrolysis products and the products were mostly gases. The materialbalances for two fractional catalytic pyrolysis runs are shown inTable 1. Compared to rapid non-catalytic pyrolysis (RP), the totalliquid yields for these runs were very low (30%), and the gas yieldswere very high (60%). The char/coke yields (11.5%) were comparable tothose reported for conventional pyrolysis of hybrid poplar wood [1].

TABLE 1 Material balance on catalytic pyrolysis of hybrid poplarfeedstock (on as received basis). Run 1461-40 Run 1461-42 Fractions #4#5 Gas Yield (%) 60 55.0 Total Liquids (%) 30.6 30.1 Char/Coke (%) 11.511.9 Total 102.1 97.0 Liquid Fractions collected Color # Phases ChilledWater 19.9 18.9 Brown 1 Condenser (g) Ice/Water 14.7 16.8 Yellow 1Condenser (g)* ESP (g) 25.7 25.3 Brown 1 Total Liquids (g) 60.3 61 Brown2 Total Biomass 197 202 Pyrolyzed (g) *This fraction had 95% water and5% dissolved organics.

Three liquid fractions from the first two condensers and the ESP thatwere very different from RP oils were obtained. The liquid from thefirst condenser was brown, with extremely low viscosity and flowedfreely at room temperature. The liquid from the second condenser waslight yellow and also had very low viscosity and appeared to be 95%water and 5% dissolved organics. The liquid from the ESP was similar tothat from the first condenser in appearance and viscosity. The liquidsfrom the first condenser and the ESP were immiscible with water andformed two phases when water was added. However, for conventionalpyrolysis, the liquid product was miscible with water. The fractionalpyrolysis oils appeared to be less viscous that the correspondingconventional rapid pyrolysis oil.

GC/MS analysis of the liquid from the first condenser and the ESP showedsimilar chemical composition. The liquids composition was almostexclusively phenolics with no detectable carbohydrate pyrolysis products(see Table 2). The constituents of the liquids from these two liquidfractions were mostly phenol, cresols, guaiacol, methyl-substitutedphenols, small quantities of indene, and substituted naphthalenes.Neither benzene, toluene, nor xylenes were detected in any of theproducts (see Table 2). These results were confirmed by ¹³C-NMR analysisof the liquid products. The ¹³C-NMR data however, showed a smallfraction of carbohydrate decomposition products in the oils. The GC/MSanalysis of the whole oil of noncatalytic pyrolysis of hybrid poplar aswell as the phenol neutral (PN) fraction extracted from the whole oilare also shown in Table 2 to illustrate the differences between theoils. Whereas the catalytic pyrolysis oil and the PN oils have very lowcarbohydrate decomposition products, the whole oil is very rich in suchproducts. The oils from the ESP and the first condenser are even richerin phenolics than the PN oil.

TABLE 2 GC/MS estimated composition of catalytic pyrolysis oils. (areacounts ×10⁶) Catalytic Non-Catalytic SG1461-040 SG1461-04 SG1461-04SG1461-04 SG1461-04 SG1461-04 Whole Run 140 Analyte 1^(st) Cond 2^(nd)Cond ESP 21^(st) Cond 22^(nd) Cond 2ESP Poplar Oil Poplar PNHydroxyacetaldehyde 0 37 0 21 19 0 46 0 Hydroxyacetone 0 32 0 0 19 0 1750 Ethanediol 0 20 0 0 10 0 0 0 2-cyclopenten-1-one 194 50 194 163 33 19124 35 3-acethyl-2cylopenten-1-one 41 0 36 30 0 32 0 0 Phenol 373 49 350333 30 356 119 222 Indan 12 0 15 10 0 13 0 13 Indene 36 0 43 32 0 46 011 2-methyl phenol (o-cresol) 239 18 234 291 11 234 30 68 4-methylphenol (p-cresol) 419 18 387 316 11 362 19 55 2-methoxy phenol(guaiacol) 60 0 61 48 0 64 29 41 methylbenzofuran 37 0 44 36 0 47 0 132,4-dimethy phenol 134 0 126 97 0 119 13 24 dimethy phenol 204 0 134 1380 176 0 17 3,5-dimethy phenol 0 0 0 0 0 0 0 0 1,2-dihydroxy benzene(catechol) 263 0 130 104 0 123 33 191 2-methoxy-4-methyl phenol(4- 0 0 00 0 0 0 0 methyl guaiacol) Naphthalene 69 0 76 68 0 79 12 02,4,6-trimethy phenol 47 0 45 38 0 44 0 20 1,2-dihydroxy-3-methylbenzene (3- 55 0 67 58 0 78 24 76 methyl catechol)dimethlylindene/trimethyl phenol 192 0 185 138 0 182 0 362-methoxy-4-ethyl phenyl(4-ethol 46 0 47 35 0 54 23 39 guaiacol)2-methyl naphthalene 169 0 184 124 0 159 0 0 1-methyl naphthalene 0 0 00 0 0 0 0 2,6-dimenthoxy phenol 113 0 143 90 0 122 61 92 Methylbenzofuran/cinnamyaldehyde 208 0 187 119 0 205 0 44 2-ethyl naphthalene0 0 0 0 0 11 14 25 dimethyl naphthalene 229 0 221 143 0 264 0 02-b-dimethoxy4-methyl phenol 164 0 152 93 0 157 43 411-(4-hydroxy-3-methoxy phenyl) 152 0 131 114 0 175 53 68 propeneLevoglucan 0 0 0 0 0 0 213 0 syringaldehyde 152 0 171 25 0 152 0 361-(3,5-dimethoxy-4-dydroxy phenyl) 174 0 278 116 0 264 61 61propene/3-methoxy-4- cinnamic acid The same mass of oil was used for allsamples analyze. The first three samples are from run 1461-40 #4, thenext three are from run 1461-42 #5. All data are raw area counls (×10⁶)but because thesame mass of sample was used the results could becompared on relative basis.

The ¹³C-NMR spectra of the two catalytic pyrolysis liquids and the RPoil are shown in FIGS. 1, 2, and 3. The signals between 0 ppm to 35 ppmwere due to side chains; signals from 60 ppm to 100 ppm derived fromcarbohydrate degradation products whereas those from 100 ppm to 160 ppmderived from lignin or phenolic compounds. The signals at 210 ppm weredue to carboxylic carbons. It is clear from FIGS. 1, 2, and 3 that thecatalytic pyrolysis liquids lost most of their carbohydrate degradationcomponents whereas the RP oil retained all those components.

It is interesting to note the difference in the height of the methoxylpeak at 58 ppm in the NMR spectra of the catalytic and non-catalyticproducts. The catalytic pyrolysis oils appeared to be less methoxylatedthan the non-catalytic pyrolysis oils. This suggests that eitherdemethylation or demethoxylation reactions took place during theprocess.

The liquid from the first condenser, which appeared to be mostly watercontained carbohydrate decomposition products such ashydroxyacetaldehyde, hydroxyacetone, ethanedial and 2-cyclopentene-1-onein addition to phenol and cresols. The product slate from this fractionwas extremely narrow and this was confirmed by the 13C-NMR results (seeFIG. 2).

The char/coke yields from these runs were low compared to those reportedfor post pyrolysis catalysis [19-26, 37]. These yields were comparableto those obtained for only the char fraction of RP solid products. Noattempt was made to distinguish between coke and char and no fartheranalysis of this solid product was carried out.

The gas yields were high compared to the RP process. The gaseous productwas a mixture of C₁-C₄ hydrocarbons, carbon monoxide (CO), and carbondioxide (CO₂). About 90% by weight of the gaseous products was CO andCO₂ and the rest was a mixture of hydrocarbons. The hydrocarbonsdetected by gas chromatography were methane, ethane, propane, butane,ethylene, and butene. Three other small peaks were present in thechromatogram but these were not identified. Butene was the most abundanthydrocarbon and in some cases constituted 30% of the total hydrocarbonproducts.

The elemental composition of the liquid products shown in Table 3 hadhigh carbon (71%) and relatively low oxygen content (21%) compared tonon-catalytic pyrolysis oils. The HHV was consequently high (30.5 MJ/kg)compared to 23 MJ/kg for the non-catalylic pyrolysis oil. Typicalnon-catalytic pyrolysis oils from hybrid poplar have 54-57% carbon and36-38% oxygen and HHVs 23-24 MJ/kg [1].

TABLE 3 Elemental composition and HHV of fractional pyrolysis liquidproducts of hybrid poplar wood. Element Composition Carbon (%) 71.32Hydrogen (%) 6.82 Oxygen (%) 21.41 Nitrogen (%) 0.24 Sulfur (%) 0.01 Ash(%) 0.09 HHV (MJ/kg) 30.5

Example 5 Molecular Weight Distribution of Liquid Products

Gel permeation chromatography (GPC) of the liquid products showed verylow molecular mass distribution of the products. The number averagemolecular weight (Mn) of the oil from the ESP and the chilled watercondenser were both 160 while the weight average molecular weight (Mw)distribution were 215 and 220 for the ESP and chilled water condenseroils respectively. The molecular mass distribution of these products wasabout one half those reported for phenol/neutral fraction ofconventional rapid pyrolysis products (Mn=290, Mw=440) (FIG. 4).

Example 6 Catalyst Activity

The CO and CO₂ concentrations appeared to vary with time during thecatalytic pyrolysis. The variation was probably due to catalystdeactivation. In these studies catalyst activity was monitored byfollowing the variation in CO and CO₂ composition in the gaseous productmixture. From the GC analysis of the gases, we compared CO/CO₂ ratio ofthe catalytic pyrolysis process with a non-catalytic pyrolysis process.The non-catalytic process was carried out in a silica sand media. TheCO/CO₂ ratio for the catalytic pyrolysis process decreased with time andappeared to approach the non-catalytic pyrolysis CO/CO₂ ratio (FIG. 5).However, the run was not carried on far enough to prove whether theactivity was asymptotic to the silica sand pyrolysis or it dropped tothat value.

The CO/CO₂ ratio varied from 2.2 to 2.8 during the runs. At the earlystages of the run, the ratio was high but gradually decreased with time.In contrast, CO/CO₂ ratio for noncatalyzed reactions was typically1.3-1.4 (see FIG. 5) and remained almost constant throughout each run.If we assume that this ratio is a true monitor of catalytic activity,then it appears the catalyst was still active after three hours runalbeit less active than the fresh catalyst. This finding is significantbecause it provides a simple method for monitoring catalyst activity.

DISCUSSION OF EXPERIMENTAL RESULTS

The fractional catalytic pyrolysis results above were compared with thenon-catalytic process, however, could such comparisons be justified? Thetwo processes could be compared because the degree of conversion wassimilar for both cases. The conversion was defined as:

$\frac{\begin{bmatrix}{{{Mass}\mspace{14mu} {of}\mspace{14mu} {Orginial}\mspace{14mu} {feed}\mspace{14mu} \left( {{raw}\mspace{14mu} {biomass}} \right)} -} \\{{Mass}\mspace{14mu} {of}\mspace{14mu} {unconverted}\mspace{14mu} {feed}}\end{bmatrix}*100}{\left\lbrack {{Mass}\mspace{14mu} {of}\mspace{14mu} {Orginial}\mspace{14mu} {feed}\mspace{14mu} \left( {{raw}\mspace{14mu} {biomass}} \right)} \right\rbrack}.$

The unconverted feed in this case was the char/ash. The char/ash for thecatalytic pyrolysis was about 11.5%, which was similar to what wasobtained for non-catalytic processes.

Under post-pyrolysis catalysis conditions, biomass feedstocks tend toproduce very high coke yields, which rapidly deactivate the catalyst[19,20,37]. The post pyrolysis catalysis liquid products usually containbenzene, toluene, xylene, naphthalenes, substituted benzene andnaphthalenic products [19,20,22]. On the contrary, in the fractionalcatalytic pyrolysis process where the catalyst and the biomass feed weremixed the catalyst was still active after 3 hours of pyrolysis and theproduct slate were quite different from those reported for postpyrolysis catalysis (see FIGS. 1&3). The total char/coke yield wasequivalent to the coke yield alone from the post pyrolysis catalysisruns [19,20,22]. The gaseous components were however similar for bothprocesses.

Clearly in the fractional catalytic process, there appeared to be aselective pyrolysis and gasification of the biomass components. Thecarbohydrate degradation products appeared to be more labile than thelignin degradation components. Thus, the carbohydrate pyrolysis productswere rapidly converted into gaseous products while the lignin pyrolysisproducts were more refractory. The gaseous products were mostly carbondioxide, carbon monoxide and C₁-C₄ hydrocarbons. As the catalyst slowlydeactivated, it appeared some carbohydrate pyrolysis products such ashydroxyacetaldehyde, ethanedial, hydroxyacetone, and cyclopeteneone werenot cracked and these condensed with the aqueous phase in the chilledwater condenser.

On the contrary, the lignin pyrolysis products underwent limitedgasification reactions and formed the bulk of the liquid products.Demethylation, demethoxylation and alkylation of the aromatic ringappeared to be the predominant reactions. The presence of highproportions of cresols and dihydroxy phenols (catechol) suggested thatdemethylation, demethoxylation and cleavage of the lignin decompositionproducts occurred. The presence of methyl and ethyl phenols in theliquid product also suggested that there might have been some alkylationreactions.

The yield of the liquid products also supported the above explanation.The total liquid yield was only 30% and the water content was 30-40%.This implies that the organic liquid yield was only 18-21%. The totallignin content of hybrid poplar wood is about 22-24% [38], and thustaking into consideration the demethoxylation reactions and loss of someside chains, the above organic liquid yield appear to be reasonable.Thus, the fractional catalytic pyrolysis appeared to favor production ofmodified liquid phenolics from the lignin fraction of the biomass whileconverting the carbohydrate fraction to gases.

Catalyst Deactivation

The absence of liquid condensate in any significant quantities duringthe first hour of pyrolysis suggested that during this phase of thepyrolysis, the catalyst was extremely active and the major reaction wasgasification. Coke formation appeared to be minimal at worst because thesum of coke and char from the pyrolysis process was only 12%. This couldbe attributed to the minimal secondary conversion of the primary ligninpyrolysis products to hydrocarbons. These suggest that the ligninpyrolysis products were mostly responsible for the coke formationreactions and thus contribute strongly to the deactivation of thecatalyst especially as obtains in post pyrolysis catalysis.

The rejection of oxygen in the feed as CO and water provides a simplemethod for following the deactivation of the catalyst. As shown in FIG.5, during non-catalytic pyrolysis, the ratio of CO/CO₂ was almostconstant and close to one, but during catalytic pyrolysis, this ratiovaried with time and approached the non-catalytic value. TI11S trendimplied that the catalyst was gradually deactivating and when thecatalyst is completely deactivated, the ratio of CO/CO₂ will be similarto that of the non-catalytic process.

CONCLUSIONS

The above demonstrates the concept of fractional pyrolysis of biomass.The most important factor is the choice of catalyst. By selecting asuitable catalyst, various components of the biomass feedstocks can beconverted in situ into desirable products. This work showed that thelignin fraction of the biomass could be effectively converted intophenolics with low char yield when catalysis and pyrolysis reactionswere performed simultaneously. Char yields for this process were similarto those obtained from conventional rapid pyrolysis. The molecular massdistribution of fractional catalytic pyrolysis process were about onehalf that obtained for phenol/neutral fraction in a conventionalpyrolysis and there appeared to be considerable demethylation anddemethoxylation reactions.

REFERENCES

-   1. Agblevor, F. A; Besler S.; Wiselogel A E, Fast pyrolysis of    stored biomass feedstocks. Energy & Fuels 1995, 9(4), 635-640.-   2. Scott, D. S.; J. Piskorz, J. Can. J. Chern. Eng. 1982, 60, 666-   3. Graham, R. G.; Bergougnou, M. A. Fast pyrolysis of biomass. J.    Anal. Appl. Pyrolysis 1984; 6, 95-135.-   4. Diebold, P J.; Scahill, 1 Production of Primary Pyrolysis Oils in    a Vortex Reactor. In Pyrolysis Oils from Biomass, Soltes, E J.;    Milne T. A., Eds.; ACS Symposium Series 376; American Chemical    Society: Washington D.C. 1988; pp 31-40.-   5. Piskorz, J.; Scott, D. S.; Radlein, D. Composition of oils    obtained by fast pyrolysis of different woods. In Pyrolysis oils    from biomass: producing, analyzing, and upgrading, Soltes, E J. and    Milne T A, Eds.; ACS Symposium Series 376; American Chemical    Society: Washington D.C. 1988; pp 167-178.-   6. Elder, T. Effect of process conditions on the yield of pyrolytic    products from southern pine. Wood and Fiber Science 1984, 16(2),    169-179.-   7. Evans, R J.; Milne T. A Molecular characterization of the    pyrolysis of biomass. 1. Fundamentals. Energy & Fuels 1987, 1(2),    123-137.-   8. Font, R.; Marcillia, A; Verdu, E.; Devesa, J. Fluidized-bed flash    pyrolysis of almond shells. Temperature influence and catalyst    screening. Ind. Eng. Chem. Prod. Res. Dev. 1986, 25, 491-496.-   9. Maschio, G.; Koufopanos, C.; Lucchesi, A. Pyrolysis, a promising    route for biomass utilization. Bioresource Technology 1992, 42,    219-231.-   10. Besler, S.; Agblevor, F.; Davis, M.; Eddy, F.; Johnson, D.;    Wiselogel, A. Fluidized bed    Pyrolysis of Terrestrial Biomass Feedstocks. In Proc. Bioenergy '94,    Sixth National Bioenergy Conference; Western Regional Biomass Energy    Program: Golden, Colo. 1994; Vol. 1, pp. 43-50.-   II. Czernik, S.; Scahill, I; Diebold, J. The production of liquid    fuel by fast pyrolysis of biomass. J Solar Energy Eng. 1995, 117,    2-6.-   12. Scott, D. S.; Piskorz, J.; Radlein, D. Liquid products from    continuous flash pyrolysis of biomass. Ind. Eng. Chem. Process    Design and Dev. 1985, 24, 581-8.-   13. Bohn, M. S.; Benham, C. B. Biomass pyrolysis with entrained flow    reactor. Ind. Eng. Chem. Process Design Dev. 1984, 23, 355-63.-   14. Scott, D. S.; Piskorz, J. The continuous flash pyrolysis of    biomass. Can. J. Chem. Eng. 1984, 62, 404-12.-   15. Diehold, J. P.; Czernik, S. Additives to lower and stabilize    viscosity of pyrolysis oils during storage. Energy & Fuels 1997,    11(5), 1081-1091.-   16. Aubin, H.; Roy, C. Study on the corrosiveness of wood pyrolysis    oils. Fuel Science International 1990, 8(1), 77-86.-   17. Agblevor, F. A; Scahill, J.; Johnson, K. D. Pyrolysis char    catalyzed destabilization of biocrude oils. In Innovative Advances    in the Forest Product Industries; Brogdon, B. N.; Hart, P. W.;    Ransdell, J. C.; Scheller, B. L., Eds.; AIChE Symposium Series 319;    American Institute of Chemical Engineers: New York, N.Y. 1998; Vol    94, pp. 146-150.-   18. Agblevor, F. A; Besler-Guran, S. Inorganic compounds in biomass    feedstocks. I. Effect on the quality of fast pyrolysis oils. Energy    & Fuels 1996, 10(2), 293-298.-   19. Agblevor, F. A.; Rejai, B.; Evans, R. J.; Johnson, K. D.    Pyrolytic Analysis and Catalytic Upgrading of Lignocellulosic    Materials by Molecular Beam Mass Spectrometry. In Energy from    Biomass and Wastes XVII. Institute of Gas Technology (IOT), Chicago,    Ill. 1993; pp. 767-795.-   20. Sharma, R K.; Bakhshi, N. N. Upgrading of wood-derived bio-oil    over HZSM-5. Biuresuurce Technul. 1991, 35(1), 57-66.-   21. Srinvas, S. T.; Dalai, A. K.; Bakhshi, N. N. Thermal and    catalytic upgrading of biomass derived oil in a dual reaction    system. Can. J. Chem. Eng. 2000, 78(2), 343-54.-   22. Sharma, R K.; Bakhshi, N. N. Catalytic upgrading of    biomass-derived oils to transportation fuels and chemicals. Can. J.    Chem. Eng. 1991, 69, 1071-81.-   23. Bahtia, V. K.; Mittal, K. G.; Mehrotra, R P.; Garg, V. K.;    Mehrotra, M.; Sarin, R. K. Catalytic conversion of Euphorbia    nerifolia biocrude into petroleum hydrocarbons. Short    Communications. Fuel 1988, 67, 1708-1709.-   24. Weisz, P. B.; Haag, W. O.; Rhodewald, P. G. Catalytic production    of high-grade fuel (gasoline) from biomass compounds by    shape-selective catalysis. Science 179, 206, 5758.-   25. Bahtia, V. K.; Padmaja, K. V.; Kamra, S; Singh, J.;    Badoni, R. P. Upgrading of biomass constituents to liquid fuels.    Fuel 1993, 72, 101-104.-   26. Diebold, J.; Scahill, J. Biomass to Gasoline: Upgrading    pyrolysis vapors to aromatic gasoline with zeolite catalysis at    atmospheric pressure. In Pyrolysis Oilsfrom Biomass; Soltes, E J.;    Milne, T. A., Eds.; ACS Symposium Series 376; American Chemical    Society: Washington: D.C., 1988; p. 264.-   27. Chum, H.; Diebold, J.; Scahill, J.; Johnson, D.; Black, S.;    Schroeder, H.; Kreibich, R. E. Biomass pyrolysis oil feedstocks for    phenolic adhesives. In Adhesives from Renewable Resources;    Hemingway, R W.; Conner, A. H.; Brabham, S J., Eds.; ACS Symposium    Series 385, American Chemical Society: Washington D.C. 1989; pp.    B5-151.-   28. Elder, J. T. The characterization and potential utilization of    phenolic compounds found in pyrolysis oil. Ph.D. Dissertation, Texas    A&M University, 1979.-   29. Russel, J.; Reinmath, W. F. Method for making adhesives from    biomass. U.S. Pat. No. 4,508,886, 1985.-   30. Rolin, A.; Richard, C.; Masson, D.; Deglise, X. Catalytic    conversion of biomass by fast pyrolysis. J. Anal. Appl. Pyrolysis    1983, 5, 151-166.-   31. Edyc, L. A; Richards, G. N.; Zheng, G. Transition metals as    catalysts for pyrolysis and gasification of biomass. Preprints, Fuel    Chemistry Division; 202nd ACS National Meetiug, New York, N.Y.    1991; p. 1715-1722.-   32. Aznar, M. P.; Corella, J.; Delgado, I; Lahoz, J. Improved steam    gasification of lignocellulosic residues in a fluidized bed with    commercial steam reforming catalyst. Ind. Eng. Chem. Res. 1993, 32,    1-10.-   33. Paisley, M. A. Anson, D. Biomass gasification for    gas-turbine-based power generation. J. Engineering/or Gas Turbines    and Power, 1998, 120(2), 284-8.-   34. Di Blasi, C.; Signorelli, G.; Portoricco, G. Countercurrent    fixed-bed gasification of biomass at laboratory scale. Ind. Eng.    Chem. Res. 1999, 38(7), 2571-81.-   35. Corella, J.; Orio, A.; Aznar, P. Biomass gasification with air    in fluidized bed: reforming of the gas composition with commercial    steam reforming catalysts. Ind. Eng. Chem. Res. 1998, 37(7),    4617-24.-   36. Agblevor, F. A.; BesJer-Guran, S.; WiseJogeJ, A. E. Production    of oxygenated fuels from biomass: impact of feedstock storage. Fuel    Science & Technol. International, 1996, 14(4), 589-612.-   37. Home, P. A.; Williams, P. T. The effect of zeolite ZSM-5    catalyst deactivation using the upgrading of biomass derived    pyrolysis vapors. J. Anal Appl. Pyrol. 1995, 34, 65-85.-   38. Milne, T. A.; Chum, H. L.; Agblevor, F.; Johnson, D. K.    Standardized Analytical Methods. Biomass & Bioenergy 1992, 2 (1-6),    341-366.

1. A fractional catalytic pyrolysis process for converting biomass intoa product slate without the need for post-pyrolysis separationcomprising: providing a catalyst bed in a fluid state, the catalystbeing maintained at a temperature suitable for pyrolysis; providing aflow of a non-reactive fluid into the catalyst bed; entraining a biomassin the flow of non-reactive fluid, so that the biomass is delivered tothe catalyst bed and pyrolyzed; and collecting the gases and vapors thatresult from the pyrolyzed biomass, wherein the gases and vapors are theresultant product slate.
 2. The fractional catalytic pyrolysis processof claim 1, wherein the catalyst is a zeolite catalyst.
 3. The factionalcatalytic pyrolysis process of claim 2, wherein the zeolite catalyst isH-ZMS-5.
 4. The fractional catalytic pyrolysis process of claim 1,wherein the catalyst is a super acid catalyst.
 5. The fractionalcatalytic pyrolysis process of claim 4, wherein the super acid catalystis a sulfated zirconium super acid catalyst.
 6. The fractional catalyticpyrolysis process of claim 1, wherein the catalyst is heated to atemperature of about 400° C. to about 650° C.
 7. The fractionalcatalytic pyrolysis process of claim 6, wherein the catalyst is heatedto a temperature of about 450° C. to about 600° C.
 8. The fractionalcatalytic pyrolysis process of claim 7, wherein the catalyst is heatedto a temperature of about 500° C.
 9. The fractional catalytic pyrolysisprocess of claim 1, wherein the non-reactive fluid is nitrogen.
 10. Thefractional catalytic pyrolysis of claim 1, wherein the non-reactivefluid is pyrolysis gas.
 11. The fractional catalytic pyrolysis processof claim 1, wherein the biomass is selected from the group consistingof: whole plant materials, biomass residues, organosolv lignins, andmixtures thereof.
 12. The fractional catalytic process of claim 1,wherein the gasses that result from the pyrolyzed biomass are collectedusing one or more condensers.
 13. The fractional catalytic process ofclaim 12, wherein the condensers are selected from the group consistingof: chilled water condensers, electrostatic precipitators, coalescencefilters, and combinations thereof.
 14. The fractional catalyticpyrolysis process of claim 1, wherein the resultant product slatecontains one or more of the following: phenols, cresols, catechols,guaiacol, methyl-substituted phenols, indene, and substitutednaphthalene.
 15. The fractional catalytic pyrolysis process of claim 1,wherein the resultant product slate contains synthesis gas.
 16. Thefractional catalytic pyrolysis process of claim 1, wherein the resultantproduct slate contains char and coke solids.
 17. The fractionalcatalytic pyrolysis process of claim 1, wherein the resultant productslate contains C₁-C₄ hydrocarbons.
 18. The fractional catalyticpyrolysis process of claim 1, wherein the lignin in the biomass areconverted primarily to phenols and cresols.
 19. The fractional catalyticpyrolysis process of claim 1, wherein the carbohydrates in the biomassare converted primarily to one or more of the following: C₁-C₄hydrocarbons, hydrogen, carbon monoxide, and carbon dioxide.
 20. Afractional catalytic pyrolysis process for converting biomass into aproduct slate without the need for post-pyrolysis separation comprising:providing a catalyst bed in a fluid state, the catalyst being maintainedat a temperature suitable for pyrolysis; providing a flow of anon-reactive fluid into the catalyst bed; entraining a biomass in theflow of non-reactive fluid, so that the biomass is delivered to thecatalyst bed and pyrolyzed; and collecting the gases and vapors thatresult from the pyrolyzed biomass using one or more condensers, whereinthe gases and vapors are the resultant product slate.
 21. The fractionalcatalytic pyrolysis process of claim 20, wherein the catalyst is azeolite catalyst.
 22. The factional catalytic pyrolysis process of claim21, wherein the zeolite catalyst is H-ZMS-5.
 23. The fractionalcatalytic pyrolysis process of claim 20, wherein the catalyst is a superacid catalyst.
 24. The fractional catalytic pyrolysis process of claim23, wherein the super acid catalyst is a sulfated zirconium super acidcatalyst.
 25. A synthesis gas produced from biomass by a low temperaturepyrolysis process, the pyrolysis process comprising: providing acatalyst bed in a fluid state, the catalyst being maintained at atemperature suitable for pyrolysis; providing a flow of a non-reactivefluid into the catalyst bed; entraining a biomass in the flow ofnon-reactive fluid, so that the biomass is delivered to the catalyst bedand pyrolyzed; and collecting the resultant synthesis gas.
 26. Thesynthesis gas of claim 25, wherein the catalyst is a zeolite catalyst.27. The synthesis gas of claim 26, wherein the zeolite catalyst isH-ZMS-5.
 28. The fractional catalytic pyrolysis process of claim 25,wherein the catalyst is a super acid catalyst.
 29. The fractionalcatalytic pyrolysis process of claim 28, wherein the super acid catalystis a sulfated zirconium super acid catalyst.
 30. The fractionalcatalytic pyrolysis process of claim 25, wherein the catalyst is heatedto a temperature of about 400° C. to about 650° C.
 31. The fractionalcatalytic pyrolysis process of claim 30, wherein the catalyst is heatedto a temperature of about 450° C. to about 600° C.
 32. The fractionalcatalytic pyrolysis process of claim 31, wherein the catalyst is heatedto a temperature of about 500° C.